1. Field of the Invention
The present invention relates to a rigid wiring board with interlayer connection and a method of manufacturing the same.
2. Discussion of the Background
In a wiring board with mounted multiple electronic components used in a cell phone or the like, connection reliability between conductive patterns is required.
However, while an electronic device is in use for a long duration, electronic components inside the electronic device may generate heat. And if the heat from the electronic components is transmitted to the resin filled in a through-hole, the resin filled in the through-hole expands and the insulation layers at the top and bottom portions of the through-hole are pushed up. In such a case, if a conductive pattern is formed either on the top or the bottom portion of the through-hole, since the insulation layer is pushed up, the conductive pattern may warp and the connection between conductive patterns may rupture. Also, by the expansion of the resin filled in the through-hole, the plating in the through-hole may be damaged and the connection between conductive patterns connected via the through-hole may rupture.
Japanese Patent Application No. 2005-199442 describes that through-holes connecting conductive patterns are formed so as to slightly curve outward at the center portion. The contents of that reference are incorporated herein by reference in their entirety.